The aims of this project are to investigate the regulation of alveolar epithelial cell function and differentiation. The factors regulating alveolar epithelial function and cell biological properties under normal circumstances and following injury are not well understood. This has been due in large part to the lack of a satisfactory in vitro model of alveolar epithelial function and differentiation, and a lack of adequate markers to confirm the state of differentiation of isolate alveolar epithelial cells. Recently, a model of cultured type II cells has been developed in this laboratory that may more closely resemble the alveolar epithelium in vivo. Isolated type II cells cultured on Nuclepore filters form tight, actively transporting monolayers and change morphologically to resemble type I cells. Concurrently they demonstrate increased binding of type I cell- specific monoclonal antibodies developed in the laboratory, suggesting a transition to the type I cell phenotype with time in culture. This model may provide a unique opportunity to investigate factors responsible for the regulation of alveolar epithelial cell function and differentiation in vitro in order to gain insight into the cell biological properties of the alveolar epithelium. Initial studies will be directed toward establishing optimal conditions for serum-free culture of alveolar epithelial cells, since serum contains a number of components that may influence alveolar epithelial cell properties. The effects of serum on the biological properties (bioelectric properties, morphology and binding of type I cell monoclonal antibodies) of cultured monolayers will be compared with those in serum-free medium. Using this model, the role of soluble growth factors and extracellular matrix factors in the regulation of alveolar epithelial function and differentiation will be elucidated. Additional cell-type specific markers will also be developed using monoclonal antibody technology. An understanding of the regulatory mechanisms involved in normal growth will facilitate our understanding of the processes involved in lung repair following injury and lend itself to the development of therapeutic interventions. The candidate is well qualified to perform this project having successfully completed clinical studies during her training related to oxidant-mediated lung injury. She will interact with several investigators who are familiar with the techniques required for the successful execution of the project and will benefit significantly from their expertise. She will be working in a supportive, protected environment where she can benefit from the resources and expertise available in other basic science laboratories at USC. These studies will provide her the opportunity to acquire additional basic science skills and will facilitate her primary goal of developing a productive research career.